<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <input type="button" value="播放" class="but">
    <br/>
    <input type="text" value="0" class="input">
    <input type="button" value="+1" onclick="ADD()">
    <input type="button" value="-1" onclick="MIN()">

</body>
<script>
    let a=document.querySelector('.but')
    a.onclick=function()
    {
        if(a.value=="播放")
        a.value="暂停"
        else a.value="播放"
    }
    function ADD()
    {
        let tmp=document.querySelector('.input')
        tmp.value=parseInt(tmp.value)+1
    }
    function MIN()
    {
        let tmp=document.querySelector('.input')
        tmp.value=parseInt(tmp.value)-1
    }
</script>
</html>